Geology of Sydney. 
20 
Ancl our existence, as a people in a new country, 
practically begins with the century. The pages of the 
great stone-book of Nature take us far back into the 
childhood of the world. By piecing together the frag- 
ments of "strange markings” on the rocks, we are able 
to picture the conditions that prevailed long before a 
block of sandstone existed where Sydney now stands. 
The sandstone cliffs, forming the gates to Port Jackson, 
attract the attention of every observer. The giant 
walls of sandstone on the Blue Mountains are sublime 
in their magnificence. But these giant walls were not 
always on the Mountains. The sea did not always 
send its rolling billows through the Port Jackson 
heads. There was a day, long ago, when there was 
no sea there to roll, and no cliffs to form headlands. 
There was a time when the highest tops of the 
mountains were depressed beneath the troubled waters 
of a great estuary. And when they finally rose in 
their grandeur to their present height or higher, 
volcanic fires lighted up the scene of Nature's 
mountain-building. Mounts Hay, Tomali, and King 
George are the remnants of a one-time continuous 
sheet of lava. This lava rose through the neck of a 
volcano, and was poured out just as fiery streams are 
seen to issue from Vesuvius or Etna to-day. Surely 
these are glimpses of a past history, more ancient than 
any written by man. But it will be asked on what 
'proven facts do these statements rest ? The cjuestion 
is best answered by an examination of the materials — 
the rocks themselves. 
